https://makezine.com/article/craft/music/how-to-wetdry-control-for-a-toy-voi/
How-To: Wet/dry control for a toy voice changer - Make:
Jul 29, 2009 - MAKE compadre Pete Edwards posted this rather handsome one-sheet guide for adding effect/mix control to a common megaphone voice changer. Looks like a
toy voice changerwet drycontrol